On the Blog and Posts page, I have my posts layout mode set to 'magazine' and number of full width posts set to '2' but none of my posts are showing full width. Here's a link to a page that should be displaying full width posts:

Firstly, a hook, as proposed in the link above is added to either the pagelines-customize/functions.php or to a child theme's functions.php, and thus should be outside the scope of any effect of Framework updates or upgrades. Thus, they're protected files and you won't lose your work.

Since the code is provided, all you'd need to do, basically, is copy and paste to the end of one of those two options. Personally, I recommend the pagelines-customize/functions.php.

The settings for full-width apply only to the blog page (or the homepage if no static homepage is created). The settings have never worked on the category page.

I've always created custom category pages using plugins, leaving the default as the backup. It's not an easy process. I truly believe you need a Pro to help with this if you want this properly built in. But if you're finding any solutions here in the forum, try those first. As you know, I proffered a solution in that referenced topic. That still applies.